The use of multiple-energy, in particular dual-energy, is increasing rapidly, for example, in medical imaging. Multiple-energy X-ray radiation can provide increased contrast in images as well as in material composition identification. An example for an approach to achieve the desired spectral separation is kV switching, generating X-ray beams of differing energy. Another example is two separate X-ray sources with different filters. However, this implies increased costs and a complicated constructional setup.